System and method for performance monitoring

ABSTRACT

A system for monitoring a computer software system includes a first user actuated tuning knob for allocating space in memory for performance monitoring; a second user actuated tuning knob for a specifying time out value for in-flight units of work; and a transaction monitor responsive to the first and second user actuated tuning knobs for accumulating in synonym chain cells in the allocated space timing statistics for a plurality of in-flight units of work.

This application is a continuation of, and claims priority to, U.S.patent application Ser. No. 10/724,327 filed 28 Nov. 2003 now U.S. Pat.No. 7,318,219 and of Ser. No. 11/906,050 filed 28 Sep. 2007, both byAllen Hall for System and Method for Performance Monitoring.

BACKGROUND OF THE INVENTION

1. Technical Field of the Invention

This invention relates to system performance monitoring. Moreparticularly, it relates to a performance monitor with user adjustabletuning bias.

2. Background Art

Referring to FIG. 1, a system and method for monitoring performance ofan information management system (IMS) 106 extends (that is, sets a hook82 in) IMS subsystem tasks 80 with non-native user code 84 and writesuser log records 88 to IMS log 86, then subsequently runs a batchtransaction transit time (TTT) calculator program 92 to post-process IMSlog 86.

The drawbacks of this technique are several. 1) Transaction transittimes are not available in real time. 2) There is a substantial DirectAccess Storage Device (DASD) 86 expense for retaining user log records88 and a substantial subset of other IMS log records 90 required to makethe TTT calculations. 3) Processing the collection of log records 88, 90requires CPU and memory to make transaction transit time calculations.If memory is exhausted, batch program 92 is terminated and TTTcalculation cannot continue. 4) Hooking the IMS sub-system could causeIMS subsystem 106 to abnormally terminate since user code 84 runs as anextension to IMS code 80.

Referring to FIG. 2, IBM performance monitor (PM) calculates inreal-time (as opposed to batch) transaction transit times (TTTs) 118 foreach individual transaction represented by a unique unit of work (UOW)104 processed by an IMS subsystem 106. An IMS subsystem 106, 108, 110 isa collection of IMS address spaces, each having characteristics similarto IMS performance monitor (PM) address space 108.

Transaction transit time (TTT) calculator task 112 requires moreresources than the sum of all other IMS performance monitor taskscombined. The number of units of work (UOW) in-flight 116 at any pointin time, available CPU resources 100, and available memory resources 102vary widely among IMS subsystem installations. IMS subsystem 106, IMS PMaddress space 108, and IMS PM data space 110 must share CPU resources100 and memory resources 102 to process and monitor IMS transactions104. Each in-flight unit of work 116 must be kept track of by in-flighttransaction vector 114 and left active in IMS PM data space 110 until itis complete and its transaction transit times 118, including input queuetime (IQT) 210, program execution time (PET) 212, and output queue time(OQT) 214 can be calculated.

The nature of performance monitoring is that the monitor itself must notimpose more CPU and memory consumption on the system than the reductionrealized by using the information it provides to tune the system.Therefore, it is important to provide users a fast-access,low-resource-impact algorithm for maintaining in memory 110 in-flightunits of work 116.

SUMMARY OF THE INVENTION

A system and method is provided for monitoring a computer application byadjustably tuning performance evaluation bias between processor andmemory consumption; and responsive to that bias, monitoring performanceof the computer application with respect to transaction transit time.

In accordance with an aspect of the invention, there is provided acomputer program product configured to be operable to monitor a computerapplication by adjustably tuning performance evaluation bias betweenprocessor and memory consumption; and responsive to that bias,monitoring performance of the computer application with respect totransaction transit time.

Other features and advantages of this invention will become apparentfrom the following detailed description of the presently preferredembodiment of the invention, taken in conjunction with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a high level schematic representation of a prior art approachfor monitoring information management services performance.

FIG. 2 is a schematic representation of the performance monitor of thepresent invention.

FIG. 3 is a schematic representation of the data space of the presentinvention.

FIG. 4 is a flow diagram of a process for determining the averages ofall TTT components for a given UP Interval.

FIGS. 5A and 5B are a flow diagram of a process for processing logrecords.

FIG. 6 is a high level system diagram illustrating a program storagedevice readable by a machine, tangibly embodying a program ofinstructions executable by a machine to perform method steps formonitoring performance with user adjustable tuning bias.

BEST MODE FOR CARRYING OUT THE INVENTION

Glossary CNT Communication Name Table DQT Destination Queue Time I/OInput/Output IMS Information Management System IQT Input Queue Time OQTOutput Queue Time PET Program Execution Time SMB Scheduler Message BlockTTT Transaction Transit Time TCB Task Control Block UOW Unit of WorkTTTTOLIM Transaction Transit Time Timeout Limit TTTDSPSZ TransactionTransit Time Data Space Size TTTSTATS Transaction Transit TimeStatistics HIMDHDS This is the name assigned to a data space (DS) block,and is not an acronym, HIMDH being an arbitrary designation HIMDCTT Thisis the name assigned to a completed transactions table (CTT), and is notan acronym, HIMD being an arbitrary designation CCPS Callable Cell PoolServices

Referring to FIG. 2, in accordance with the preferred embodiment of theinvention, users 120 are provided tuning knobs 122 with which to biasthe operation of a performance monitor toward CPU resource consumption(via setting TTTTOLIM 126) or memory resource consumption (via settingTTTDSPSZ 124) so that the algorithm makes the best use of the CPU andmemory resources 100, 102 of a particular installation. Users areprovided feedback in the form of resource consumption statistics 128 onthe effects of the bias selected so that further refinements can bemade. The feedback is recorded over time so that the resourceconsumption by the algorithm can be examined during times of peak IMSsubsystem transaction workload.

If memory resources 102 are exhausted, the algorithm simply waits untilmore memory 102 is available to continue transaction transit timecalculation and informs user 120 that this has occurred. TTT calculatortask 112 builds a hash table referred to as in-flight transaction vector114 which anchors synonym chains of in-flight transaction (UOW) cells116. These two data structures are implemented in data space 110 usingoperating system provided facility of callable cell pool services.

Hash tables and synonym chains are commonly used data structures and aredescribed by Donald Knuth, Art of Computer Programming.

The performance monitor (PM) address space 108 does not performTransaction Transit Time calculation as an extension (hook) to IS code106. It runs under its own task control block (TCB) 112 in its ownaddress space 108 and therefore runs no risk of terminating the IMSsubsystem 106 abnormally, which is critical to business operation.

Transaction transit time (TTT) data structure 114 is kept in data space110. It is primarily a hash table where synonym chains (linked lists)116 are anchored to vectors in a hash table 114 (See FIG. 3).

Hash table 114 can be tuned for either a CPU 100 or a memory 102resource constrained system. User 120 provides a number of megabytes (ISPM parameter TTTDSPSZ) 124 to allocate to the data space 110. For eachmegabyte provided, the hash table 114 has allocated to it 1024 vectors,each anchoring a separate hash, or synonym, chain 116. Each vector 114is addressed via hashing a transaction unit of work (UOW) ID to a hashkey, where there are as many different hash keys as there are vectors invector table 114. Therefore the number of hash keys is 1024 times thenumber of megabytes 124 allocated to data space 110. The more keys inhash table 114, the faster the access to the in-flight units of work116, but at the expense of memory 110. The fewer the keys, the lower thememory usage in the data space 110, but at the expense of CPU 100consumption to run the hash chains 116 to find the in-flight UOW thatmust be processed.

Said another way, the higher the percent utilization of memory resources102 by data space 110 (given as feedback 128), the greater the number ofCPU 100 cycles it takes to locate hash table 114 and process eachin-flight UOW in synonym chains 116. The inverse also applies, but atthe expense of memory resources 102. Therefore, if the system is morememory constrained than processor constrained, user 120 targets forhigher percent utilization by setting TTTDSPSZ 124 to a lower number. Ifthe system is more CPU 100 constrained than memory 102 constrained, user120 targets for a lower percent utilization by setting TTTDSPSZ 124 to ahigher number. If the system is both processor and memory constrained,the user may choose to target for around 50% utilization (given asfeedback 128) during peak load times of IS in-flight UOWs. If the systemis not constrained, TTTDSPSZ 124 is set equal to the maximum allowed.

A second way to tune this structure is via the TTTTOLIM 126 value, whichis the time-out value for in-flight unit of work on synonym chain 116.Setting a low number of seconds before timeout (TTTTOLIM) causes a unitof work to be flushed out of the data space 110 sooner thus decreasing %Utilization given as feedback 128.

In this example, the default for TTTDSPSZ 124 is one megabyte, whichallows the $HIMDHDS data space 110 to be allocated on any system withoutuser intervention. Users display consumption statistics 128 on aperiodic basis by issuing a DISPLAY TTTSTATS command to track percentutilization over the course of an IS subsystem workday. The statisticsdisplayed in Table 1 are appended by monitor 108 to a sequential dataset 128 with a time-stamp. Users 120 examine the statistics in Table 1as appended to sequential dataset 128 and determine if TTTDSPSZ 124should be increased because % utilization exceeds 50% during peaks inIMS workloads or if it could be reduced thus decreasing memory (dataspace) 110 usage with no impact to CPU 100 consumption.

Table 1 illustrates two examples of DISPLAY TTTSTATS command outputs.

TABLE 1 DISPLAY TTTSTATS COMMAND OUTPUTS Date: 11/15/2003 Time: 07:04:42HIM01031 TZETZE: Transaction Transit Time Stats Data space % Utilization(10 Meg): 000% Maximum # Trans In Flight: 00000735 Current # Trans InFlight: 00000458 Possible # Trans In Flight: 00073721 Total TransCompleted Normally: 00013136 Total Trans Completed Timed Out: 00000000Total Out Limit Secs. (TTTTOLIM): 00086400 Date: 11/15/2003 Time:10:17:07 HIM01031 TZETZE: Transaction Transit Time Stats Data space %Utilization (10 Meg): 000% Maximum # Trans In Flight: 00000735 Current #Trans In Flight: 00000458 Possible # Trans In Flight: 00073721 TotalTrans Completed Normally: 00013987 Total Trans Completed Time Out:00000000 Time Out Limit Secs. (TTTTOLIM): 00086400

As seen in the example of Table 1, the Data space 110 % utilizationnever reached even 1%. Also, the 10 megabyte data space 110 canaccommodate up to 73,721 in-flight transactions 116; that is, 7372 permeg. Since 735 is less than 10% of 73721, then a 1 megabyte data space(very small relative to typical data spaces) is under the 50% targetlimit. The user would then set TTTDSPSZ 124 equal to 1 to reduce memoryusage with virtually no effect on CPU consumption.

The four transaction transit time (TTT) components 118 include inputqueue time (IQT) 210, program execution time (PET) 212, output queuetime (OQT) 214, and total transaction transit time (TTTT) 216. Inaddition, for program switches, the number of switches may be tracked.Maximum, average and minimum values for each of these four componentsare tracked in a statistics database by calculator task 112. If any ofthe totals accumulated for any of the TTT 118 components cause overflow(i.e. wrap), then all totals are reinitialized and accumulation beginsagain. Referring to FIG. 3, IQT 210, PET 212, OQT 214 and TTTT 216 arecalculated for each UOW 104 input to a scheduler message block SMB 270and output to a communication name table CNT 268. Performance monitor108 is single-tasked, so log records 280 arrive in the order IS createsthem.

Referring to FIG. 2, a UOW log record 104 includes length, record type,record subtype, record content, clock, and log sequence number (LSN)fields.

Startup parameters, or tuning knobs, 122 which may be set by user 120 toadjust tuning bias between memory and CPU usage by the performancemonitor, include data space size allocation 124, and timeout value 126.

Data space size allocation 124 is the size, in megabytes, allocated tothe TAT DH Data space 132. The default is one. Each megabyte canaccommodate approximately 7,300 in-flight transaction instance units ofwork (UOW) 156.

Timeout value 126 for in-flight units of work 116 is the limit in numberof seconds (up to 24 hours) a transaction instance, or unit of work(UOW), 116 is allowed to remain in-flight before it is timed out. If thein-transit time of the UOW exceeds TTTTOLIM 126, that is, when currenttime minus UOW arrival time exceeds the TTTTOLIM 126, it is timed out.Time out means that TTTTOLIM 126 is substituted for either programexecution time (PET) 212, if the UOW 116 is still in program execution,or output queue time (OQT) 214 if the UOW is still on the output queue.The UOW being timed out is then considered complete and its input queuetime (IQT) 210, PET 212, OQT 214, and TTTT 216 values are accumulatedinto TTT components database 118 for its associated transaction code.The time out process prevents a single problematic UOW from having ahigh impact on the averaged TTT components for a particular transactioncode.

When viewing in performance statistics 118 the maximum program executiontime or maximum output queue time for a transaction code it is possiblefor user 120 to determine if time out processing occurred for one ormore UOW if either of them is equal to TTTTOLIM 126 (converted tomilliseconds). The number of UOWs timed out is also part of the view118. If a UOW times out on the input queue it is flushed since it neveractually began execution.

Referring to FIG. 4, by way of example for TTT, averages of all TTTcomponents 118 for a given interval are calculated by PM 108 code asfollows:

In step 220, user 120 selects a transaction code and an interval; e.g.between 8:00-a.m. & 9:00 a.m.

In step 222, history file 118 is read to get the two TTT componentsamples for transaction codes written closest to A) 8:00 and B) 9:00.

In step 224, the number of transactions in the interval is determined:total # transactions in interval=total # transactions from sampleB−total # transactions from sample A.

In step 226, the total input queue time 210 is determined: total IQT ininterval=total IQT from sample B−total IQT from sample A.

In step 228, the average IQT is determined in the interval: average IQTin interval=total IQT in interval/total # transactions in interval.

In step 230, for average IQT for a particular transaction code, PMdisplays in columns for transaction codes the total # transactions ininterval and the average IQT in interval.

A similar process is used for calculating PET, OQT, and TTTT.

Referring to FIG. 3, all TTT data structures, except HIMDHDS 130, arestored in $HIMDHDS data space 110.

A DISPLAY TTTSTATS command processor is executed to format thestatistics that are stored in HIMDHDS block 130 for presentation to user120 as resource consumption statistics 128.

TTT DH primary memory structures include data space control blockHIMDHDS 130, in-flight transaction vectors HIMDITV 114, completedtransactions table HIMDCTT 118, and in-flight transaction cells HIMDITC116, 150.

In-flight transaction cells HIMDITC 116, 150 and their synonym chainvectors in the in-flight transaction vector table HIMDITV 114 functionas follows.

When the TTT calculator task 112 is called to integrate a log record104, in-flight transaction cells (ITCs) 116, 184 for the correspondingUOWs 104 are updated with time stamps from log records 104. UOWs arehashed to one of the 1024 hash keys (or multiple of 1024 thereof) togain access to the UOW Synonym Chain 116 of ITCs. (The multiple is equalto TTTDSPSZ 124.) This results in more hash keys for larger dataspacesthus keeping the UOW lookups fast in a system which is not memory boundand which is, therefore, tuned to optimize CPU usage.) The hash key isused as an index into HIMDITV 114. HIMDITV 114 contains vectors ITV1 . .. ITVN in an area of data space 110 where synonym chains 116 reside.Synonym chains 116 are made up of linked lists of HIMDITCS 182, 184, oneHIMDITC per in-flight UOW and are segregated into 1 megabyte CCPS areaextents 176, 178, 180.

When the TTT calculator task 112 is called to return the TTT components210, 212, 214, 216 of completed transactions, the contents of HIMDCTTtable 118 are sent to user 120.

Data space block HIMDHDS 130 contains data space access, performance,usage and user parameter information. It also contains information onthe CCPS anchor 170 and the CCPS extent management blocks 172 requiredfor callable cell pool services to manage in-flight transaction cellsHIMDITCS 116 in data space 110. Enough information is maintained toallow a user to see when the data space 110 allocated pursuant toTTTDSPSZ allocation size 124 is reaching maximum capacity.

To put a log record into TTT data space 110, an integrate call takes acaptured log record and stores its UOW information into the TTTin-flight UOW data structures 114, 116 in data space 110.

During the integrate call TTTTOLIM 126 is used in a garbage collectionprocess to clean up in-flight UOWs 182, 184 that are incomplete due tosome type of unexpected, unanticipated, or new IMS workload that doesnot generate the expected set of log records 104. The time out valueTTTOLIM 126 is compared with the difference between the current time anda UOW's arrival time is taken from the log record time stamp in order todetermine if the UOW has “Timed Out.” This comparison is done for achain of in-flight transaction cells 116 anchored to its in-flighttransaction vector 114 each time a new cell 116 is added to a vector's114 chain. In this way, garbage collection is not done all at once, butone vector 114 at a time.

Referring further to FIG. 3, in-flight transaction vectors HIMDITV 114and the initial completed transactions table HIMDCTT 118 are allocatedin fixed contiguous virtual addresses below the 1 megabyte line in the$HIMDHDS data space 110 immediately after callable cell pool services(CCPS) control information (including anchor 170 and extent managementblocks (EMBs) 172). There is only one CCPS Anchor 170 (64 bytes). Thereis one CCPS Extent Management Block (EMB1, EMB2, . . . ) 172 per 1megabyte specified via TTTDSPSZ 124. The remainder of data space 110 isallocated to CCPS to manage the cells used to contain the synonym chains116 of HIMDITCS 182, 184 and to contain additional HIMDCTT entries 118should they be required. More HIMDCTTs 118 may be required if moredifferent transaction code names complete than there were HIMDCTTentries CCTTRAN1 . . . CCTTRAN1000 initially allocated. The DCTT 118 isa block of pre-chained CTT entries and more are allocated from cells indata space 110 if required.

At minimum a 1 megabyte data space 110 (actually 239 pages since this isthe MVS default for maximum data space size) is allocated and formattedduring initialization. These first 239 pages contain CCPS anchor 170,extent management blocks 172 (fixed size), in-flight transaction vectorsHIMDITV 114 (variable size), and completed transactions HIMDCTT 118(fixed size) with the remainder allotted to cells 116 of HIMDITCS. This1 meg minimum corresponds to a data space size allocation 124 ofTTTDSPSZ=1.

As is illustrated in FIG. 3, for TTTDSPSZ 124 equal to three (3),additional megabytes specified on TTTDSPSZ 124 are broken into 1megabyte CCPS extent cell areas 178, 180. The new extent areas 178, 180contain exclusively additional HIMDITC and HIMDCTT cells.

HIMDITCS 182 for a UOW 104 are added to the front of synonym chains 150anchored in HIMDITV 114. In the example of FIG. 3, currently only twoUOWs 182, 184 are in-flight. The most recent UOW 182 added to the chainis the most likely one to complete; i.e. high volume transactions go onand off the synonym chains 150 more frequently than low volumetransactions. This results is faster UOW lookups in synonym chain 116.CCPS satisfies consecutive cell requests from adjacent data spacevirtual addresses. Therefore, adding HIMDITCS 182 to the front ofsynonym chain 150 yields close proximity page references when accessinga particular synonym chain 150.

When using cell pool services to manage the HIMDITCS 182, 184 in the$HIMDHDS Data space 110, an anchor 170, extent management blocks 172,extents 176, 178, 180, and cells 182, 184 are required. Anchor 170 is,in this exemplary embodiment, 64 bytes. The first extent managementblock EMB1 requires 128 bytes plus one byte for every eight cells in thefirst extent 176. Subsequent extent management blocks EMB2, EMB3 eachrequire 128 bytes plus one byte for every eight cells in subsequent 1megabyte extents 178, 180.

To obtain the location where the first cell storage 184 in the 1stextent 176 starts, add the data space origin Address (0 or 4096)+AnchorSize (64 bytes)+Length Of All Extent Management Blocks+Length ofHIMDITV+Length of the HIMDCTT. The address of the end of the last Cell182 in the first extent 176 is calculated so that a starting point forsubsequent Extents 178 is known.

Cell Pool Services Calls are used to build a cell pool (CRSPBLD), add anextent and connect it to its cells (CRSPEXT), get cells for use(CRSPGET) and free cells (CRSPFRE). All extents 176, 178, 180 areconnected during the Initialize Call.

HIMDHDS 130 contains information required to allocate, access, and checkthe performance of the $HIMDHDS Data space 110. The first page of dataspace 110 is reserved for CCPS control information since it is necessaryto know this value (4096) before the calculation of the number ofHIMDCTTs 118 that will fit in data space 110.

Table 2 sets forth several HIMDHDS fields that are set during the TTT DHinitialization call.

TABLE 2 HIMDHDS FIELDS HIMDHDS DSECT HDSNAME “$HIMDHDS” Data space NameHDSMSCD A(HIMMSCD) HDSTOKN: STOKED HDSTTOK: TOKEN HDSALET: LET HDSORIG:ORIGIN of DSP (0 or 4K) HDSDSPSZ: TTTDSPSZ In Number of Megabytes (fromproclib) HDSTTOLM: TTTTOLIM = UOW Timeout Value in Seconds. (fromproclib) HDSGCOEF: Garbage Collection Coefficient. Used during TTTTOLIMprecessing as a divisor into ITVUOWNM. If the remainder is 0 then thesynonym chain is cleared of all UOWA that have Timed Out; e.g. Dogarbage collection every 100th time a new UOW is added to a SynonymChain. HDSDSIZE: DSP Size = 4K * (239 + ((TTTDSPSZ − 1) × 256)))HDSDITVR # Rows in the HIMDITV (1024 × TTTDSPSZ) HDSDITVL HIMDITV Length= (Len(HIMDITV Prefix) + (HDSDITTR * (HIMDITV Row Length)) HDSDCTTR #Rows in the HIMDCTT at startup HDSDCTTL HIMDCTT Length = (Length(HIMDCTTPrefix) + HDSDCCTR * (Len(HIMDCTT Row)) HDSDITV@ A(HIMDITV) = HDSCRESV(> CAPS reserve of 4K) HDSDCTT@ After HIMDITV@ = (HDSITV@ + HDSITVL)HDSDCST@ CPPS Cells Starting Address = End of HDSDCTT = HDSDCTT@ +HDCDCTTL HDSDC1ND =239 * 4K − 1 = End of Cells in First Extent HDSCTEXT:# CAPS Total Extents (=TTTDSPSZ) HDSCCSZ Calces = Length(HIMDITC)HDSCANSZ Size of CAPS Anchor = 64 bytes. HDSCRESV =4096; Reserve 1 Pagefor CAPS Control Information HDSC1EXT # Cells in the 1st extent =(HDSDCEND − HDSCDST@)/HDSCCSZ HDSC1EXS Size of 1st extent mgt block =128 + (# Cells in 1st Extent/8) HDSCXEXT # Cells in subsequent 1 megextents = (1M − 1)/ HDSCCSZ HDSCXEXS Size of subsequent extent mgtblocks = 128 + (HDSCXEXT/8) HDSUOWCP Total number of UOW's added asHIMDCTTs. HDSUOWMX Max # of UOWA in flight at any one time; CS duringIntegrate OR Call HDSUOWCR Current # of UOWA in flight; CS duringIntegrate OR Call HDSUOWTO Possible # UOWA in flight; allows for %utilization calculation. HDSUOWGC # of UOWA flushed during GarbageCollection; UOW was Timed Out, yet not enough info. To be added toHIMDCTT HDSUOWTO # of UOWA Timed Out yet enough info to be added toHIMDCTT; CS

In-flight transaction vector table HIMDITV 114 is anchored to theHIMDHDS 130 and has by default 1024×TTTDSPSZ rows. As outlined above,the most precise word of bits in UOW 104, bits 20-51 (with bit 51incremented every microsecond), are hashed to a hash key from 0-1023 (orTTTDSP multiple thereof). That key is used to locate the HIMDITV 114vector ITV1 to the associated HIMDITC synonym chain 150 of in-flight UOW182, 184.

Table 3 sets forth the format of the HIMDITV block 114, which is set upby an initialization call to the TTT calculator task 112.

TABLE 3 IN-FLIGHT TRANSACTION VECTORS HIMDITV FORMAT HIMDITV DSECTITVPRFX ADIT.: “ditv” ITVDHDS@ Address of HIMDHDS ITVHCTT@ Address ofHIMDCTT ITVUOWNM: Number of ITVROWS (1024 × TTTDSPSZ) ITVPRFXL#: EquateLength of ITVPRFX ITVROW EAU * ITVITCVT Vector to first HIMDITC inSynonym Chain of HIMDITC cells ITVUMAX Maximum Number of UOWA In-Flighton Chain at any one time ADVENA Current Number of UOWA In-Flight onChain ITVLRNM Total # UOWA integrated onto Synonym Chain ITVUOWNM: #Completed UOW taken from Synonym Chain ITVFLUSHS Number of UOW's flusheddue to TTTTOLIM including unexpected Log Record patterns/ workloads.ITVROW# Equate Length off ITVROW

In-flight transaction cells HIMDITC 116 addresses are provided via callsto CCPS and, for example, are part of synonym chains 150 anchored toentry ITV1 in HIMDITV 114. If no matching UOW is found on chain 150,then a new HIMDITC 182 is added to the head of the synonym chain 150.

When a UOW's complete set of log records 104 arrives, TTT calculatortask 112 calculates TTT components 210, 212, 214, and 216 and summarizesthem in a HIMDCTT 118 entry for the corresponding transaction andcorresponding HIMDITC entry 182 is removed from the chain 150. Its cell,say 182, is then returned to CCPS for reuse.

Table 4 sets forth the format of an in-flight transaction cell HIMDITC116, 182, 184.

TABLE 4 IN-FLIGHT TRANSACTION CELL HIMDITC FORMAT HIMDITC DSECT ITCNEXT:Pointer to next HIMDITC on UOW Hash Chain ITCUOW: 1st 16 bytes of UOW ofIn-Flight UOW (AMSTEAD + STCK) ITCTRNCD: Transaction Code of In-FlightUOW ITCFLAGS: Only In chain 01 Arrived, First in Chain 01 Arrived, LastIn Chain 01 Arrived, M.C. Locally Processed, M.C. Externally Processed,Originating Program Switch, Resultant Program Switch ITCLRMSK: Maskindicating which Log Records have arrived: 01, 03, 35, 31(1), 31(2)ITCTYPE: Type of Processing UOW involved in: PGMSW, SMQ1IMS, SMQ2IMSITCIDSTN: Input CUT/MISNAME to be compared to 35 rec Output CUT/MISNAMEITCARRIV: U.C. Transaction Arrival Time from 01 ITCS ART: U.C.Transaction Processing Start Time from Get Unique 31 from DL/I ApplITCENDT: U.C. Transaction Processing End Time from 35 when ENQUEUES toCUT/MISNAME ITCOUTQ: U.C. Output Transaction Sent Time from DC Com.Manager 31 ITCPGMSW: Number of Program Switches from 03 ITCSEQNM: last 4bytes of Log Sequence Numbers 294 of above Log SECS 280 for debuggingpurposes.

Completed transaction table HIMDCTT 118, which is displayed to users byIMSPM, is anchored to and positioned after the HIMDITV 116 in the dataspace 110. Each entry CCTTRAN1 . . . CCTTRAN1000 contains a transactioncode and its associated TTT Components 210, 212, 214, and 216. Theinitial HIMDCTT block 118 has as a somewhat arbitrary (say 1000) butreasonable number of entries. Additional entries are chained in asrequire when more that 1000 new transaction code names complete. Theinitialization call to the TTT DH formats the initial HIMDCTT 118 andpre-chains the entries CCTTRAN1 . . . CCTTRAN1000 together.

A new entry is added to the end of the HIMDCTT 118 when a uniquetransaction code completes. When a UOW 104 completes, this list 118 isscanned for the matching transaction code. The first attempt for a matchis at CTTLMTCH which is maintained as the last matching transactionentry. This speeds updates since the last matching transaction is themost likely one to next complete. If this fails, the table 118 isscanned sequentially from the beginning. If the matching transactioncode is not encountered then a new CTT 118 ROW CCTTRAN(>1000) is addedas a data space 110 cell and chained to the end.

Table 5 sets forth the format of completed transactions table HIMDCTT118.

TABLE 5 COMPLETED TRANSACTIONS TABLE HIMDCTT FORMAT HIMDCTT DSECTCTTPRFX CTT Prefix Containing Status Information CTT ID “dctt” CTTITV@Address of HIMDITV CTTHDS@ Address of HIMDHDS CTTLMTCH Pointer to CTTROW that last matched a completed UOW. Speeds updates. CTTLMTNM Numberof times CTTLMTCH found the correct transaction code. CTTPRFX# EquateLength of CTTPRFX CTT ROW DS 0H CTTTRNCD Transaction Code CTTTRTOTTransaction Coders total number of completed transactions CTTTRTO OfCompleted Transactions this many Timed Out on Output Queue CTTIQTTOTotal Input Q Time CTTIQTMX Maximum Input Q Time CTTIQTMN Minimum InputQ Time CTTPETTO Total Program Execution Time CTTPETMX Maximum ProgramExecution Time CTTPETMN Minimum Program Execution Time CTTOQTTO TotalOutput Q Time CTTOQTMX Maximum Output Q Time CTTOQTMN Minimum Output QTime CTTTTTTO Total of Total Transit Times CTTTTTMN Minimum TotalTransit Time CTTTTTMX Maximum Total Transit Time CTTPGMSW Total NumberProgram Switches CTTPGMSX Maximum Number Program Switches CTTPGMSNMinimum Number Program Switches CTRL@ Length of one CTT Row

Referring to FIGS. 5A and 5B, log records 104 are processed by the TTTcalculator task 112 as follows.

In step 239, the log records 104 are examined to filter out those whichare of no interest. This reduces the set of log records to a point thatthey are as determinate as possible regarding the set required tocomplete a UOW 104 and store it in the HIMDCTTT 118.

In step 240, calculator task 112 receives a log record 104 from IMS.

In step 246, the UOW 104 is hashed and in step 248 its synonym chain 150located in the HIMDITV 114. This is done by searching the HIMDITVsynonym chain 114 of HIMDITC'S for the UOW 104. If it exists, in step252 relevant TTT data is captured from the log record 104 and put in theHIMDITC 184, and the flag set in the HIMDITC 184 (see Table 4)corresponding to the log record 104 processed. If it does not exist, instep 250 a new HIMDITC synonym chain 150 block 182 is chained in at thehead of the chain 150, and then in step 252 the log record 104information captured.

When in step 254 it is determined that the log records 104 required tocomplete a transaction have all arrived, in step 256 the HIMDCTT block118 is updated with the TTT data 160 and in step 258 the HIMDITC 184 isremoved from the HIMDITV synonym chain 150.

Incomplete UOWs 104 are flushed from chain 150 for one of two reasons:(A) A long running transaction has exceeded some predetermined limit(TTTTOLIM=) 126 and enough information is available to infer TTT 118data; and (B) When a UOW 104 has insufficient information to determineTTT data due to some unexpected log record pattern. This is part of thegarbage collection process.

ALTERNATIVE EMBODIMENTS

It will be appreciated that, although specific embodiments of theinvention have been described herein for purposes of illustration,various modifications may be made without departing from the spirit andscope of the invention. Referring to FIG. 6, in particular, it is withinthe scope of the invention to provide a computer program product orprogram element, or a program storage or memory device 200 such as asolid or fluid transmission medium, magnetic or optical wire, tape ordisc, or the like, for storing signals readable by a machine as isillustrated by line 202, for controlling the operation of a computer204, such as a host system or storage controller, according to themethod of the invention and/or to structure its components in accordancewith the system of the invention.

Further, each step of the method may be executed on any general purposecomputer, such as IBM Systems designated as series, series, series, andseries, or the like and pursuant to one or more, or a part of one ormore, program elements, modules or objects generated from anyprogramming language, such as C++, Java, Pl/1, Fortran or the like. Andstill further, each said step, or a file or object or the likeimplementing each said step, may be executed by special purpose hardwareor a circuit module designed for that purpose.

Accordingly, the scope of protection of this invention is limited onlyby the following claims and their equivalents.

1. A host computer system comprising a processor, the host computersystem for monitoring a computer software system by reading log recordswritten by said software system to determine performance of saidsoftware system relative to response time to end users, the hostcomputer comprising: a first user actuated tuning knob for allocatingspace in memory for performance monitoring; a second user actuatedtuning knob for a specifying time out value for in-flight units of work;a transaction monitor responsive to said first and second user actuatedtuning knobs for accumulating, in synonym chain cells in said space,timing statistics for a plurality of said in-flight units of work; saidmemory including an in-flight transactions vector table for anchoringsynonym chains of in-flight transaction cells; said in-flighttransaction cells for accumulating time statistics for in-flighttransactions; said memory including a completed transactions table forstoring time statistics for completed transactions; a monitor forreceiving from said computer software system a transaction log recordfor a unit of work; said monitor hashing said first transaction logrecord to select from said vector table an anchor to an in-flighttransaction cells chain corresponding to said unit of work; said monitorfor searching said in-flight transaction cells chain for said unit ofwork; said monitor further responsive to finding said unit of work insaid in-flight transaction cells chain for capturing to said in-flighttransaction cell timing statistics from said transaction log record;said monitor further responsive to not finding said unit of work in saidin-flight transaction cells chain for chaining a new in-flighttransaction cell to said chain and capturing to said new in-flighttransaction cell timing statistics from said transaction log record;said monitor further for determining if said transaction log recordcompletes a transaction and, if so, updating said completed transactionstable with timing statistics for said transaction and removing saidin-flight transaction cell from said in-flight transaction cells chain;and said monitor further for determining responsive to said secondtuning knob if a selected unit of work being accumulated in a selectedin-flight transaction cell has timed out, and if so removing from saidselected in-flight transaction cell from said in-flight transaction cellchain and selectively updating said completed transactions table withtiming statistics for said selected unit of work.
 2. A program storagedevice readable by a machine, tangibly embodying a program ofinstructions executable by a machine to perform method steps formonitoring a computer software system by reading log records written bysaid software system to determine performance of said software systemrelative to response time to end users, said method comprising:adjustably tuning performance evaluation bias between processor andmemory consumption; responsive to said bias, monitoring performance ofsaid computer software system with respect to transaction timeparameters; receiving from a user a first tuning parameter forallocating memory for said monitoring performance and a second tuningparameter for specifying time out for in-flight units of work;initializing said memory with an in-flight transactions vector table foranchoring synonym chains of in-flight transaction cells; accumulatingtime statistics for in-flight transactions in said in-flight transactioncells; initializing said memory with a completed transactions table forstoring time statistics for completed transactions; receiving from saidcomputer software system a transaction log record for a unit of work;hashing said first transaction log record to select from said vectortable an anchor to an in-flight transaction cells chain corresponding tosaid unit of work; searching said in-flight transaction cells chain forsaid unit of work; responsive to finding said unit of work in saidin-flight transaction cells chain, capturing to said in-flighttransaction cell timing statistics from said transaction log record;responsive to not finding said unit of work in said in-flighttransaction cells chain, chaining a new in-flight transaction cell tosaid chain and capturing to said new in-flight transaction cell timingstatistics from said transaction log record; and determining if saidtransaction log record completes a transaction and, if so, updating saidcompleted transactions table with timing statistics for said transactionand removing said in-flight transaction cell from said in-flighttransaction cells chain.
 3. A program storage device readable by amachine, tangibly embodying a program of instructions executable by amachine to perform method steps for monitoring a computer softwaresystem by reading log records written by said software system todetermine performance of said software system relative to response timeto end users, said method comprising: adjustably tuning performanceevaluation bias between processor and memory consumption; responsive tosaid bias, monitoring performance of said computer software system withrespect to transaction time parameters; receiving from a user a firsttuning parameter for allocating memory for said monitoring performanceand a second tuning parameter for specifying time out for in-flightunits of work; initializing said memory with an in-flight transactionsvector table for anchoring synonym chains of in-flight transactioncells; accumulating time statistics for in-flight transactions in saidin-flight transaction cells; initializing said memory with a completedtransactions table for storing time statistics for completedtransactions; receiving from said computer software system a transactionlog record for a unit of work; hashing said first transaction log recordto select from said vector table an anchor to an in-flight transactioncells chain corresponding to said unit of work; searching said in-flighttransaction cells chain for said unit of work; responsive to findingsaid unit of work in said in-flight transaction cells chain, capturingto said in-flight transaction cell timing statistics from saidtransaction log record; responsive to not finding said unit of work insaid in-flight transaction cells chain, chaining a new in-flighttransaction cell to said chain and capturing to said new in-flighttransaction cell timing statistics from said transaction log record;determining if said transaction log record completes a transaction and,if so, updating said completed transactions table with timing statisticsfor said transaction and removing said in-flight transaction cell fromsaid in-flight transaction cells chain; and determining responsive tosaid second tuning parameter if a selected unit of work beingaccumulated in a selected in-flight transaction cell has timed out, andif so removing from said selected in-flight transaction cell from saidin-flight transaction cell chain and selectively updating said completedtransactions table with timing statistics for said selected unit ofwork.